Wireless local area networks (“WLANs”) can give clients the ability to “roam” or physically move from place to place without being connected by wires. In the context of a WLAN, the term “roaming” describes the act of moving between wireless access devices, which may be stand-alone wireless access points that cooperate with infrastructure located in the WLAN. Many deployments of wireless computer infrastructure, such as WLANs, involve the use of multiple wireless access devices serving a number of mobile client devices.
A wireless local area network (“WLAN”) relies on infrastructure components that establish associations such as data communication links with mobile client devices. A mobile client device communicates, via a wireless data communication channel, with an access point device, which in turn communicates with other network components via traditional wired interfaces. A WLAN infrastructure may be configured to support a plurality of mobile clients using a single access point device. In other words, one access point device can support a plurality of different groups or categories of client devices each with a wide range of possible data rate or bandwidth requirements.
Most WLANs are governed by IEEE specification 802.11. The different variants of IEEE 802.11 are incorporated by reference herein. To form an association such as a data communication link between a mobile client device and a wireless access point, a mobile client device will require an active channel for transmitting data for at least one of the media type access categories such as the WMM/WME access categories of video, voice, best-effort, and/or background. The Wireless Multimedia/Wireless Multimedia Extension (WMM/WME) Specification (by Wi-Fi Alliance; www.wi-fi.org) provides for the distribution of WMM/WME parameters to mobile users in 802.11. Any WMM/WME documentation publicly available from Wi-Fi Alliance, either online or otherwise, and IEEE Standard 802.11 (all variants) are incorporated by reference herein. In particular, “Wi-Fi CERTIFIED™ for WMM™—Support for Multimedia Applications with Quality of Service in Wi-Fi® Networks,” Wi-Fi Alliance (Sep. 1, 2004) is incorporated by reference herein.
The 802.11b and 802.1 μg protocols divide their designated spectrum (the FCC ISM band) into 14 channels with specified center frequencies 5 megahertz (MHz) apart. Existing IEEE 802.11 protocol devices utilize default channels assigned by country or international agreement. The channels that are available for use in a particular country differ according to the regulations of that country. In the United States, for example, FCC regulations only allow channels 1 through 11 to be used. In Europe, channels 1-13 are licensed for 802.11b operation. The default channel assignment may be communicated by an 802.11d international roaming information element.
802.11 devices may use all available channels, but in practice, two or three channels (active channels) are actually used by access points or ad hoc stations and networks. In this regard, 802.11 devices may spend significant time and power searching for networks on unused channels. This may cause out-of-band interference resulting in reduced data rate during data communications in congested networks. It is desirable to have a way to assign active channels for 802.11 devices. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.